Pushbutton actuator for elastomeric switch



May 7, 1968 P. ARSENEAULT ETAL ,3 PUSHBUTTON ACTUATOR FOR ELASTOMERIC SWITCH Filed April 26, 1966 FIG. 1

2 INVENTORS PAUL ARSENEAULT SlLVlO U. BLASKOVIC LARRY G. LANKEORD ATTORNEY United States Patent 3,382,338 PUSHBUTTON ACTUATOR FOR ELASTOMERIC SWITCH Paul Arseneault, Wappingers Falls, Silvio U. Blaskovic, Yorktown Heights, and Larry G. Lankford, Mahopac, N .Y., assignors to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed Apr. 26, 1966, Ser. No. 545,330 '8 Claims. (Cl. 200-159) ABSTRACT OF THE DISCLOSURE An elastomeric diaphragm type switch wherein there is included a rigid non-deformable member such as a sphere on an elastic diaphragm of the switch opposite to one of its contacts and an elastically deformable member disposed on the rigid member. In operation, the button of the switch, upon being depressed, is made to bear against the elastically deformable member, the latter member suitably being of a material such as neoprene. With this arrangement, there is thereby incorporated the need for a discernible stroke displacement which is essentially absent in the operation of sensitive diaphragm switches and thereby provides a familiar and comfortable sensation to the operators.

The present invention relates to keyboard switch devices and more particularly to a mechanism for actuating elastomeric switches.

There is a type of device presently available known as an elastomeric switch. A typical elastomeric switch includes a first elastomeric layer having rows of conductive strips aflixed thereto and a second layer having similar conductive strips. The two layers are separated by an insulating layer having apertures at the crosspoints of the conductive strips. To close the switch at any given crosspoint the elastomeric layer is depressed at that point and the two conductive strips are brought into contact. An elastomeric switch is shown and described in copending US. patent application Ser. No. 442,758, filed Mar. 25, 1965, now Patent No. 3,308,253, by M. Krakinowski and assigned to the present assignee.

If the elastomeric switch contains N conductive rows and N conductive columns, then there can be N crosspoints, each of which can be actuated by a pressure applied normal to the elastomeric layer. It has been found that it requires very little displacement of the elastomeric layer to effect the closure of the conductive strips, and in fact, when the closure is done by manual pressure, the person operating the switch discerns no physical displacement. Since the majority of mechanical and electromechanical keyboards presently available provide a discernible stroke displacement when manipulated, operators have found that the lack of stroke displacement experienced when operating an elastomeric switch is unfamiliar and uncomfortable to the point of affecting efiiciency.

An object of the present invention is to provide an improved mechanism for actuating an elastomeric switch device.

Another object of the present invention is to provide a mechanism in combination with an elastomeric switch device which provides physical key travel, both depression and return.

A further object of the present invention is to provide a mechanism in combination with an elastomeric switch device which provides elasticity for key travel and rigidity for concentrating switch closure pressure.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a sectional side view of an embodiment of the present invention in its repose state.

FIG. 2 is a sectional side view detail of an elastomeric switch used in FIG. 1.

Referring to FIG. 1, an elastomeric switch mechanism is shown including an elastomeric switch 8 having four separate layers 10, 14, 18, and 22. In FIG 2 a detail of the elastomeric switch is shown wherein layer 10 is a substrate or support having a segment of conductive material 12 plated on its upper surface; layer 14 is composed of an insulating material having an opening 16 in the area of the conducting material 12, layer 18 is a diaphragm positioned on top of layer 14 and a conducting material 20 is fixed to the underside of layer 18 in the area of the opening 16; and layer 22 is composed of an elastomeric material and is positioned over layer 18. A layer of lubricant 24 is provided between diaphragm 18 and elastomeric material 22.

When pressure is applied to the upper surface of the elastomeric material 22 in the area above the opening 16, both the elastomeric layer 22 and the diaphragm 18 will deform downward into the opening 16 and conducting material 20 is brought into contact with conducting material 12. It should be appreciated that conducting material 20 and 12 can be adapted to function as electrical switch contacts.

Referring again to FIG. 1, a mechanism is provided in combination with elastomeric switch 8 including a lightweight plate 26, for example aluminum or plastic, positioned over the upper layer 22 of the elastomeric switch 8. The plate 26 contains apertures 28 passing completely through the plate in the area above the openings 16 (see FIG. 2) of the elastomeric switch 8. The plate 26 further includes counterbored holes 30 located above the apertures 28 and having a much greater diameter. Alternatively, plate 26 may be composed of two separate layers, one having apertures 28 and the other having holes 30. Located within each of the apertures 28 is a metallic or ceramic nondeformable ball 32 which rests on the elastomeric layer 22. A relatively thick elastomeric layer 34 is located above the layer 26 and above the elastomeric layer 34 are located a plurality of key assemblies 36, each key or button being disposed above a separate aperture in plate 26. When any of the key assemblies are manually depressed, pressure will be applied through the stem 38 to the elastomeric layer 34. The elastomeric layer 34 will compress and ultimately be forced down into the counterbored holes 30 thereby applying pressure to the ball 32 which is displaced downwardly onto the elastomeric layer 22 of the switch 8 causing the conducting material therein to make contact as previously described. The combination of the elastomeric layer 34 and the ball 32 allows a degree of key travel while the switch is being actuated and imparts the proper psychological feel to the operator. The compressibility of the elastomeric layer 34 permits the key travel or stroke and the pressure transmitted therethrough is applied to the ball and concentrated at the point of contact between the ball and the top layer of the elastomeric switch. When the manual pressure is removed from the key assembly, the elastomeric layer 34 returns to its original shape thereby raising the key assembly to its initial position.

Another feature which can be incorporated in the present invention is shown in FIG. 1 by a metallic disk 40 affixed to the bottom of the elastomeric layer 34 above the ball 32. When the diameter of the disk is equal to the diameter of the bottom of the key stem, the manual pressure transmitted from the key stem through the elastomeric layer 34 and the disk 40 onto the ball 32 is in the ratio of one to one. If a diminished pressure is desired, that is if less pressure is required to depress the ball onto the switch 8 than is normally applied by the operator, then the disk 40 can be made smaller in diameter with respect to the diameter of the bottom of the key stern and the manual pressure applied to the key and the pressure imparted to the ball below will be proportional to the ratio of the area of the bottom of the key stem to the area of the disk. The entire mechanism including the switch 8 may be enclosed in a suitable enclosure 42 thereby forming a compact keyboard unit.

What has been described is a unique mechanism for actuating elastomeric switches which provides for key travel and produces the proper feel to an operator. The mechanism also concentrates the applied pressure at the proper area above the switch and includes a feature whereby the key is returned to its original position when manual pressure is removed.

For the purpose of providing a complete explanation, examples of some materials and dimensions of a typical embodiment of the present invention are provided as follows:

Substrate 10, glass or epoxy lami- While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An apparatus for actuating an elastomeric switch device comprising:

an elastomeric switch device including at least one pair of opposed electrical contacts, one of said contacts being connected to an elastic diaphragm,

at least one rigid nondeformable member disposed on said elastic diaphragm opposite to said one of said contacts,

an elastic deformable member disposed on said rigid member opposite to said elastic diaphragm,

and at least one movable means mounted on said elastic deformable member for applying pressure through said elastic deformable member and said rigid member to said elastic diaphragm to move said elastic diaphragm and effect closure of said pair of electrical contacts when said movable means is depressed.

2. An apparatus according to claim 1 wherein said rigid nondeformable member is a ball located between said elastic diaphragm and said elastic deformable member opposite said pair of contacts.

3. An apparatus according to claim 1 wherein said elastic deformable member is a layer of resilient material located between said movable member and said rigid nondeformable member for compressing in response to pressure produced by the depression of said movable memher and transferring said pressure produced by said movable member to said rigid nondeformable member.

4. An apparatus according to claim 3 wherein said layer of resilient material expands to its original form when pressure from said movable member is removed.

5. An apparatus according to claim 3 wherein said rigid nondeformable member is a ball located between said layer of resilient material and said elastic diaphragm opposite said pair of contacts and responsive to said pressure transferred through said resilient layer for depressing said elastic diaphragm and closing said pair of electrical contacts.

6. An apparatus according to claim 5 further including a second nondeformable member mounted to said layer of resilient material opposite to said ball for transferring said pressure from said resilient layer to said ball.

7. An apparatus according to claim 6 wherein said second nondeformable member is a rigid disk.

8. An apparatus according to claim 5 wherein said elastomeric switch device includes a plurality of opposed electrical contacts, one of each of said plurality of contacts being connected to one side of said elastic diaphragm,

an apertured plate mounted on the other side of said elastic diaphragm, said plate having a plurality of apertures therethrough, each aperture being opposite a separate one of said plurality of contacts connected to said elastic diaphragm,

a separate ball located in each of said plurality of apertures in said plate between said elastic diaphragm and said elastic deformable member,

and a separate movable means mounted on said elastic deformable member opposite each of said balls.

References Cited UNITED STATES PATENTS 2,192,296 3/1940 Boynton 200159 2,916,563 12/1959 Bernstein 200-159 XR 2,981,816 4/1961 Cozart 200-159 3,308,253 3/1967 Krakinowski 200-46 ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

